What are some words you associate with the phrase "temporary tattoo?" Probably things like "boardwalk," "awesome," "vacation," "crooked," and "flaky." If you're talking about henna tattoos, however, your temporary tattoo word cloud might include things like: "hives," "boils," and "rash." That's because, according to a statement released Monday by the Food and Drug Administration, black henna dye might cause a longer-lasting allergic reaction, riddling your sun-burnished vacation skin with "oozing lesions."

According to the Los Angeles Times, there's an extra ingredient in the longer-lingering black henna dye — hair dye including p-phenylenediamine, or PPD. An FDA report further explains that PPD can trigger allergic reactions in some people, "including redness, blisters, oozing lesions, increased sensitivity to sunlight and permanent scarring." Those lovely side effects can occur right after the dye is applied, or as many as two to three weeks later.

The Times' Eryn Brown notes that black henna, which is "often used at tourist destinations and other specialty shops," is not the same as the reddish-brown henna "that comes from the flowering plant Lawsonia inermis, which is native to tropical and subtropical regions of Africa and Asia." A key ingredient in the gullible tourist henna is PPD, which helps make the tattoo last longer than it otherwise would.

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The latest FDA report follows a recent study in the snappily-named Journal of the German Scientific Society of Dermatology that identified PPD as the source of seven subjects' allergic reactions to hair and eyelash dyeing. All subjects had histories of sensitization to PPD after receiving black henna tattoos, but their reactions to hair dye took about six years "post-sensitization" to appear.